Collaborative Research: Prediction of Medusan Predatory Roles Based on Quantitative Studies of Animal-Fluid Interactions

一些研究发现，美杜莎捕食在各种海洋浮游生物群落中起着主导作用，但控制美杜莎猎物选择和摄食率的变量仍然存在争议。这种缺乏共识的一个可能原因是，对水母捕食的机制理解不强，而不是单一的统一类型，水母是一个多样化的系统发育、形态和功能的捕食者阵列，在构建现实的捕食者模型之前，必须了解它们的机械差异。本研究将检验一种假设，即功能选择的多样性仅限于medusan运动的两种主要机械解决方案：喷射推进和划船推进。研究人员认为，这些推进类型是理解捕食模式的关键，因为推进模式与觅食模式直接相关。然而，这提出了主要的挑战，因为只有喷气推进在水母中被定量描述过。相比之下，所有记录在案的水母限制浮游生物存量的例子都涉及划桨推进的、巡航的水母，它们在游泳时通过猎物携带的液体捕食。研究人员认为，量化流体与美杜莎猎物捕获表面的相互作用是建立预测美杜莎猎物选择和摄食率的现实模型的必要前提。该项目的第一个目标是定量描述划桨和喷射推进的水动力特性。这将涉及一项跨学科的比较研究，使用自由游泳动物的DPIV测量和新开发的方法来分析和解释这些定量流动可视化。根据这些结果，研究人员将推导出适用于主要水母谱系的适当的水动力学模型。第二个主要目标是定量描述流体流动和最具生态影响力的水母谱系（划桨推进的巡航觅食者）捕获表面之间的相互作用。这一群体的成员包括各种各样的血统，它们要么在游钟周围的上游（如Narcomedusae， Coronatae）捕获猎物，要么在下游（如Leptomedusae， Semastomeae, rhizzostomeae）捕获猎物。这项研究将详细描述过去捕获表面的流体流速，并将作为基于水动力学的水母捕食清除率估计的基础。拟议活动的智力价值：美杜莎捕食影响所有浮游生物群体，基于水动力学对美杜莎捕食的理解的发展将潜在地广泛应用于其他浮游生物分类群的研究。此外，这些信息将为动物游泳和综合海洋动物行为领域提供新的概念见解。从这个角度来看，本研究直接解决了理解海洋系统中影响生物多样性的因素及其生态后果的问题，这是美国国家科学基金会生物海洋学部门强调的一个特定主题。此外，阐明海洋运动控制设计原则可以补充现有的受鱼类游泳启发的水下航行器设计研究。拟议活动的更广泛影响：学生，主要是本科生，将参与拟议研究的各个方面，研究人员将参与旨在将这些培训和指导机会指导给代表性不足的本科生的项目。参与此次合作的两位主要研究人员主要来自本科院校，一位主要来自研究生院校。加州理工学院的既定项目旨在为来自全国其他校区的少数族裔学生提供研究机会，将鼓励代表性不足的本科生参与其中。这位加州理工学院的研究员还将继续担任加州理工学院新生暑期学院（FSI）研究项目的协调员。这个为期四周的年度项目于2001年启动，旨在应对来自弱势群体的学生参与校园研究活动的比例过低的问题。此外，他们还将利用与大众教育媒体的联系，向公众宣传我们关于美杜珊形状和功能的新发现。最后，我们将开发一个在线教程，将新的实验DPIV方法传播给其他研究小组，研究水生生物力学和海洋生态学的各种主题。

Several studies have found that medusan predation plays a dominant role in a variety of marine planktonic communities, but the variables controlling medusan prey selection and ingestion rates remain contentious. A possible reason for this lack of consensus is that there is not a strong mechanistic understanding of medusan predation and, rather than a single uniform type, medusae are a diverse phylogenetic, morphological and functional array of predators whose mechanical differences must be understood before realistic predator models can be constructed. This study will examine the hypothesis that the diversity of functional alternatives are constrained to two major mechanical solutions for medusan motility: jetting and rowing propulsion. The investigators argue that these propulsion types are the key to understanding predation patterns because propulsive mode is directly related to foraging mode. However, this presents a major challenge because only jet propulsion has been quantitatively described in medusae. In contrast, all of the documented examples of planktonic standing stock limitation by medusae involve rowing-propelled, cruising medusae that feed by fluid entrainment of prey during swimming. The investigators contend that quantification of fluid interactions with medusan prey capture surfaces is a necessary prerequisite to the construction of realistic models predicting medusan prey selection and ingestion rates. The first goal of the project is to quantitatively delineate hydrodynamic characteristics of rowing and jetting propulsion. This will involve an interdisciplinary comparative study of representative members of major medusan lineages using DPIV measurements of free-swimming animals and newly developed methods for the analysis and interpretation of these quantitative flow visualizations. From these results, the investigators will deduce appropriate hydrodynamic models for application to major medusan lineages. The second major goal is to quantitatively describe the interactions between fluid flows and capture surfaces of the most ecologically influential medusan lineages - the rowing-propelled, cruising foragers. Members of this group include various lineages that capture prey in either the upstream (e.g. Narcomedusae, Coronatae) or downstream (e.g. Leptomedusae, Semastomeae, Rhizostomeae) components of flow around the swimming bell. This research will detail the fluid flow rates past capture surfaces and will serve as the basis for hydrodynamically-based clearance rate estimates of medusan predation.Intellectual Merit of the Proposed Activity: Medusan predation affects all planktonic groups, and development of a hydrodynamically based understanding of medusan predation will have potentially wide application to studies of other planktonic taxa. Additionally, this information will contribute novel conceptual insights to the fields of animal swimming and integrated marine animal behavior. From this perspective, this study directly addresses the issue of understanding factors influencing biological diversity and its ecological consequences in marine systems, a specific theme emphasized by NSF's Biological Oceanography division. Furthermore, the elucidation of governing design principles in marine locomotion can complement existing studies of underwater vehicle design inspired by fish swimming.Broader impacts of the Proposed Activity: Students, primarily undergraduates, will participate in every aspect of the proposed research and the investigators will participate in programs designed to direct these opportunities for training and mentorship toward underrepresented undergraduate students. Two of the principal investigators participating in this collaboration are from primarily undergraduate institutions and one is from a primarily graduate institution. The participation of underrepresented undergraduate students will be encouraged through established programs at Caltech aimed at providing research opportunities to minority students from other campuses across the country. The Caltech investigator will also continue in his role as Coordinator of the Freshmen Summer Institute (FSI) Research Program at Caltech. This annual, four-week program was initiated in 2001 in response to the disproportionately low number of students from underrepresented groups participating in research activities on campus. In addition, they will use their contacts with media involved in education of the general public to communicate our new findings about medusan form and function. Finally, an online tutorial will be developed to disseminate the new experimental DPIV methods to other research groups investigating various topics in aquatic biomechanics and marine ecology.